- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Giant Stark effect in coupled quantum wells: Analytical model
摘要： Coupled quantum wells have been proposed as candidates for highly polarizable structures due to their near-degenerate and dipole-coupled electronic states. Hence, many interesting applications in linear and nonlinear optics can be envisioned. We analyze this proposal considering a simple structure with a delta-function barrier separating the wells. While very substantial Stark shifts are certainly predicted for this geometry, perturbative estimates based on polarizabilities (and hyperpolarizabilities) fail beyond a critical ?eld strength that depends inversely on the barrier. Hence, a giant Stark effect due to near-degenerate states is invariably limited by a small critical ?eld. Our analytical (hyper) polarizability expressions are applied to ?nd quantitative Stark shifts for GaAs quantum wells and transition-metal dichalcogenide bilayers. The predicted Stark shifts and critical ?elds agree with the ?eld dependence observed in a range of available experiments.
关键词： Stark effect,hyperpolarizability,GaAs,transition-metal dichalcogenide bilayers,polarizability,coupled quantum wells
更新于2025-09-23 15:19:57
-
Electron-hole superfluidity controlled by a periodic potential
摘要： We propose controlling an electron-hole super?uid in semiconductor coupled quantum wells and double layers of a two-dimensional (2D) material by an external periodic ?eld. This can be created either by the gates periodically located and attached to the quantum wells or double layers of the 2D material or by the moiré pattern of two twisted layers. The dependence of the electron-hole pairing order parameter on the temperature, the charge carrier density, and the gate parameters is obtained by minimization of the mean-?eld free energy. The second-order phase transition between super?uid and electron-hole plasma, controlled by the external periodic gate ?eld, is analyzed for different parameters.
关键词： mean-?eld free energy,semiconductor coupled quantum wells,electron-hole super?uid,phase transition,external periodic ?eld,two-dimensional material
更新于2025-09-11 14:15:04